What Happens to the Food I Eat?
Our bodies get energy and nutrients from food.
Before our bodies can use these
nutrients, the food has to be broken down into simple substances that can be absorbed
into our blood. The nutrients are then taken to the cells in our bodies where they can be
used. This process by which food is broken down into simpler substances is called
digestion.
The system that digests food in our bodies is called the digestive system.
The
process of digestion takes place as the food passes through the alimentary canal
which is a long tube made up of muscles that begins at the mouth and ends at the
anus.
Below is a diagram that shows different parts of the alimentary canal.
The digestion of food begins in the mouth. Food is crushed as it is chewed, saliva
mixes with the food and begins to change starch into sugar. The tongue then rolls the
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food into a ball called a bolus and pushes it to the back of the mouth where it is
swallowed. The food passes from the mouth into a narrow muscular tube called the
gullet or esophagus. The gullet has muscles that contract and squeeze the food so
that it passes down the tube to the stomach.
The stomach is a sack made of muscles, were food is stored for a while. The muscles of
the stomach contract and relax, mixing the food with digestive juices produced by the
walls of the stomach. This causes further digestion of the food as some of its nutrients
are broken down into simpler substances.
The food, which is now liquid, passes from the stomach into the small intestines. This
is the area in the alimentary canal where most digestion takes place. The liver and the
pancreas are two organs in the body that produce digestive juices that are added to the
food causing other substances in the food to break down into simpler substances. The
food is now ready to be absorbed into the body. As the food passes through the small
intestines it is absorbed into the blood stream.
There are some parts of food that cannot be broken down and absorbed. This is mainly
fibre which is made up of indigestible vegetable matter. This passes into the large
intestines along with other undigested food.
There water, minerals and salts are
absorbed and the semi-solid waste called faeces that remain eventually pass into the
rectum where it is stored until it is passed out of the body through the anus.
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